Distillers research terroir in grain

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Terroir is traditionally a wine concept, the idea that the flavor of the ingredient (grapes) and thus the end product is a reflection of place. The modern brewing and distilling approach to starch sources (grain), on the other hand, prioritizes agronomic factors, such as yield, and mathouse/brewhouse perfomance.

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The American Malting Barley Association, for example, is an organization of producers (growers, maltsters) and consumers (primarily brewers, but also including Leopold Brothers Distillery). For a long time AMBA was the purview of macro growers and producers, though craft maltsters and craft brewers have been joining in greater numbers.

Every year, AMBA releases recommendations on commercial malt criteria, and it is telling that the recommendations include barley factors, malt factors, malt modification, enzymes, and wort composition, but makes zero reference to flavor.

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It should be made clear that this is not a diatribe against AMBA or any other organization that encourages effective, if uninteresting, grain. The organization will come up in multiple articles in the Local Grain Network as the antithesis of location-based, flavor-driven grain sourcing. Nonetheless, the list of AMBA-approved varieties that is release at the beginning of every calendar year provides real help to farmers and users who are looking for reliability and consistency.

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Some distillers and researchers, though, are taking an analytical approach to the intersection of variety, location, and flavor in products where terroir was traditionally not considered, or was considered to be a non-factor.

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Rob Arnold, head distiller at Firestone and Robertson Distilling, published a research paper last year examining the intersection of varietal and environment for corn grown in four locations around Texas, finding that “variety, terroir and their interactions … can substantially affect valuable sensory aspects of whiskey.”

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Arnold’s research, as a part of his Ph.D. studies at Texas A&M, analyzed four commercial varieties of yellow dent corn grown in four locations spread across Texas — in Calhoun, Hansford, Hidalgo, and Hill counties.

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His research found a particular relationship, even using commercial varieties, between variety, location and the compounds benzaldehyde (almond-y) and decanal (fruity) in raw corn samples. Benzaldehyde especially was linked to higher levels of desirable congeners such as isoamyl acetate and ethyl octanoate.

The link between benzaldehyde and other congener formation is key because bnzaldehyde can be measured using gas chromatography-mass spectroscopy without having to ferment and distill spirit to be tested. Because of this, it may be valuable as a marker in selecting corn varieties in the future.

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Meanwhile, the Whiskey Terroir Project, a research endeavor conducted by Waterford Distillery in Ireland, Dustin Herb of Oregon State University, Teagasc (an Irish state research/advisory agency), and Enterprise Ireland, is examining the correlation of location and barley variety with flavor over two growing seasons.

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Two barley varieties, Olympus and Laureate, were both grown at two different sites, in Bunclody and Athy, Ireland. The second-season results are still being analyzed, but the results of the first year are available here. While the two varieties performed similarly in the malthouse, the soil composition appeared to play a tangible role in flavor differences.

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With higher trace levels of barium, cadmium, zinc, copper and aluminum, the Bunclody samples of grain showed more fruity character in sensory analysis, with aromas that included fruity, apple pear, yeasty, earthy, nutty, and bubble gum. Athy grain had higher levels of selenium, chromium, and tin, with aromas that included bready, almond, caramel, woody, and phenolic.

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Gas chromatography indicated an environmental impact on production of acetaldehyde, methanol, n-propanol, n-butanol and furfural. Athy had higher levels of furfural, which shares the same aroma descriptors already noted, while Bunclody had higher levels of n-propanol, which also corresponds to aroma notes of musty, fruity, apple, pear, bubble gum.

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There were also differences based on varietal, with Olympus creating more ethyl laurate (floral, creamy, fruity), and variations resulting from the interaction of variety and environment, with Laureate grown in Athy and Olympus grown in Bunclody both showing increased ethyl lactate (fruity, tart, butterscotch aromas, creamy caramel flavor).